Distorted Inverse Spinel Nickel Cobaltite Grown ona MoS 2 Plate for Significantly Improved Water SplittingActivity

Sluggish water dissociation kinetics on nonprecious metal oxide electrocatalysts is considered as the rate-limiting step for the development of hydrogen evolution in alkaline media. A unique heterostructure, a distorted inverse spinel Ni–Co–O layer on MoS2 plate, was developed in this paper. The formation of Mo–O–Co covalent bonds at the interface allows for the inherent electron transfer from MoS2 to the adjacent surface spinel and forces the nucleation and creation of disordered inverse spinel. Such a crystal-distorted structure enables the substantially improved activity for hydrogen evolution reaction (HER) by more than 40 times and oxygen evolution reaction (OER) by 2.5 times compared to the regular spinel nickel cobaltite. Through a comprehensive kinetics study, the results reveal that this inverse spinel layer promotes the water dissociation process and the intrinsic HER activity by decreasing the apparent activation energy barrier Ea, increasing the exchange current density j0, and improving the c...